The object of the invention is a method for breaking ice, a motor-driven trimaran and use of the trimaran for breaking ice.
By trimaran is meant a ship, boat or other watercraft, which has three hulls. In this application the terms middle hull and side hulls are used for the hulls. Trimarans are known both as sailing and motor vessels. The purpose of the three hulls of the trimaran is to increase the stability of the watercraft. Three hulls also make possible the formation of a large deck area.
Most of the prior art trimarans are not designed to move in icy conditions and they function very poorly in ice conditions. If one manages to break ice with the prior art trimaran, three separate grooves are easily formed in the ice and the broken ice fragments are packed between the hulls of the watercraft. Thereby the total breaking resistance becomes large. Most ice-breaking vessels have one hull, but for the purpose of the ice-breaking properties, decisions have to be made concerning their hull shapes, which decisions deteriorate the open water properties of the watercraft.
In patent publication RU 2171203 C1 is shown a trimaran, to the bow of which is attached a hydraulic ice-breaking apparatus. Ice-separating wedges, which open in the direction of the side hulls, are arranged in the middle hull of the watercraft. Hydrofoils are arranged between the middle and side hulls. Ice is cut at the front of the watercraft into suitably sized fragments with a hydraulic ice-cutting device. The water under the hulls is saturated with air and with the aid of the hydrofoils the trimaran is lifted onto the ice, after which the ice cut by the cutting device is crushed by the weight of the watercraft. This solution is very complicated, especially because it requires an ice-cutting device and an airbag to be attached to the bow of the trimaran. In addition, the trimaran with its ice-cutting apparatus according to the publication is poorly suited for other use than ice cutting.